December 2, 2017
Welcome to Django 2.0!
These release notes cover the new features, as well as some backwards incompatible changes you’ll want to be aware of when upgrading from Django 1.11 or earlier. We’ve dropped some features that have reached the end of their deprecation cycle, and we’ve begun the deprecation process for some features.
This release starts Django’s use of a loose form of semantic versioning, but there aren’t any major backwards incompatible changes that might be expected of a 2.0 release. Upgrading should be a similar amount of effort as past feature releases.
See the Upgrading Django to a newer version guide if you’re updating an existing project.
Django 2.0 supports Python 3.4, 3.5, 3.6, and 3.7. We highly recommend and only officially support the latest release of each series.
The Django 1.11.x series is the last to support Python 2.7.
Django 2.0 will be the last release series to support Python 3.4. If you plan a deployment of Python 3.4 beyond the end-of-life for Django 2.0 (April 2019), stick with Django 1.11 LTS (supported until April 2020) instead. Note, however, that the end-of-life for Python 3.4 is March 2019.
Following the release of Django 2.0, we suggest that third-party app authors
drop support for all versions of Django prior to 1.11. At that time, you should
be able to run your package’s tests using python -Wd so that deprecation
warnings do appear. After making the deprecation warning fixes, your app should
be compatible with Django 2.0.
The new django.urls.path() function allows a simpler, more readable URL
routing syntax. For example, this example from previous Django releases:
url(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),
could be written as:
path('articles/<int:year>/', views.year_archive),
The new syntax supports type coercion of URL parameters. In the example, the
view will receive the year keyword argument as an integer rather than as
a string. Also, the URLs that will match are slightly less constrained in the
rewritten example. For example, the year 10000 will now match since the year
integers aren’t constrained to be exactly four digits long as they are in the
regular expression.
The django.conf.urls.url() function from previous versions is now available
as django.urls.re_path(). The old location remains for backwards
compatibility, without an imminent deprecation. The old
django.conf.urls.include() function is now importable from django.urls
so you can use from django.urls import include, path, re_path in your
URLconfs.
The URL dispatcher document is rewritten to feature the new syntax and provide more details.
contrib.admin¶The admin is now responsive and supports all major mobile devices. Older browsers may experience varying levels of graceful degradation.
The new Window expression allows
adding an OVER clause to querysets. You can use window functions and aggregate functions in
the expression.
django.contrib.admin¶ModelAdmin.autocomplete_fields attribute and
ModelAdmin.get_autocomplete_fields() method allow using a
Select2 search widget for ForeignKey and
ManyToManyField.django.contrib.auth¶django.contrib.gis¶AsGeoJSON function,
GeoHash function,
IsValid function,
isvalid lookup, and distance lookups.Azimuth and
LineLocatePoint functions,
supported on PostGIS and SpatiaLite.GEOSGeometry imported from GeoJSON now
has its SRID set.OSMWidget.default_zoom attribute to customize the map’s
default zoom level.metadata,
info, and
metadata attributes.GDALRaster objects using papsz_options.GDALRaster objects in
GDAL’s internal virtual filesystem. Rasters can now be created from and
converted to binary data in-memory.GDALBand.color_interp() method returns the color
interpretation for the band.django.contrib.postgres¶distinct argument for
ArrayAgg determines if
concatenated values will be distinct.RandomUUID database
function returns a version 4 UUID. It requires use of PostgreSQL’s
pgcrypto extension which can be activated using the new
CryptoExtension migration
operation.django.contrib.postgres.indexes.GinIndex now supports the
fastupdate and gin_pending_list_limit parameters.GistIndex class allows
creating GiST indexes in the database. The new
BtreeGistExtension migration
operation installs the btree_gist extension to add support for operator
classes that aren’t built-in.inspectdb can now introspect JSONField and various
RangeFields (django.contrib.postgres must be in INSTALLED_APPS).django.contrib.sitemaps¶protocol keyword argument to the
GenericSitemap constructor.cache.set_many() now returns a list of keys that failed to be inserted.
For the built-in backends, failed inserts can only happen on memcached.File.open() can be used as a context
manager, e.g. with file.open() as f:.date_attrs and time_attrs arguments for
SplitDateTimeWidget and
SplitHiddenDateTimeWidget allow specifying different
HTML attributes for the DateInput and TimeInput (or hidden)
subwidgets.Form.errors.get_json_data() method returns form errors as
a dictionary suitable for including in a JSON response.ContextMixin.extra_context attribute allows adding context
in View.as_view().inspectdb now translates MySQL’s unsigned integer columns to
PositiveIntegerField or PositiveSmallIntegerField.makemessages --add-location option controls the comment
format in PO files.loaddata can now read from stdin.diffsettings --output option allows formatting the output
in a unified diff format.inspectdb can now introspect AutoField if the
column is created as an identity column.dbshell now supports client-side TLS certificates.squashmigrations --squashed-name option allows naming the
squashed migration.StrIndex database function
finds the starting index of a string inside another string.AutoField and BigAutoField are now created as identity
columns.chunk_size parameter of QuerySet.iterator() controls the
number of rows fetched by the Python database client when streaming results
from the database. For databases that don’t support server-side cursors, it
controls the number of results Django fetches from the database adapter.QuerySet.earliest(), QuerySet.latest(), and
Meta.get_latest_by now
allow ordering by several fields.ExtractQuarter function to
extract the quarter from DateField and
DateTimeField, and exposed it through the
quarter lookup.TruncQuarter function to
truncate DateField and
DateTimeField to the first day of a quarter.db_tablespace parameter to
class-based indexes.Extract now works with
DurationField.of argument to QuerySet.select_for_update(), supported
on PostgreSQL and Oracle, to lock only rows from specific tables rather than
all selected tables. It may be helpful particularly when
select_for_update() is used in conjunction with
select_related().field_name parameter of QuerySet.in_bulk() allows fetching
results based on any unique model field.CursorWrapper.callproc() now takes an optional dictionary of keyword
parameters, if the backend supports this feature. Of Django’s built-in
backends, only Oracle supports it.connection.execute_wrapper() method allows
installing wrappers around execution of database queries.filter argument for built-in aggregates allows adding
different conditionals to multiple aggregations
over the same fields or relations.Meta.ordering.named parameter of QuerySet.values_list() allows fetching
results as named tuples.FilteredRelation class allows adding an ON clause to
querysets.Paginator.get_page()
to provide the documented pattern of handling invalid page numbers.Engine.get_default() in third-party
apps, it now returns the first engine if multiple DjangoTemplates engines
are configured in TEMPLATES rather than raising ImproperlyConfigured.LiveServerTestCase.DATAFILE_SIZE, DATAFILE_TMP_SIZE,
DATAFILE_EXTSIZE, and DATAFILE_TMP_EXTSIZE.ProhibitNullCharactersValidator disallows the null
character in the input of the CharField form field
and its subclasses. Null character input was observed from vulnerability
scanning tools. Most databases silently discard null characters, but
psycopg2 2.7+ raises an exception when trying to save a null character to
a char/text field with PostgreSQL.To support native Python 2 strings, older Django versions had to accept both
bytestrings and unicode strings. Now that Python 2 support is dropped,
bytestrings should only be encountered around input/output boundaries (handling
of binary fields or HTTP streams, for example). You might have to update your
code to limit bytestring usage to a minimum, as Django no longer accepts
bytestrings in certain code paths. Python’s -b option may help detect
that mistake in your code.
For example, reverse() now uses str() instead of force_text() to
coerce the args and kwargs it receives, prior to their placement in
the URL. For bytestrings, this creates a string with an undesired b prefix
as well as additional quotes (str(b'foo') is "b'foo'"). To adapt, call
decode() on the bytestring before passing it to reverse().
This section describes changes that may be needed in third-party database backends.
DatabaseOperations.datetime_cast_date_sql(),
datetime_cast_time_sql(), datetime_trunc_sql(),
datetime_extract_sql(), and date_interval_sql() methods now return
only the SQL to perform the operation instead of SQL and a list of
parameters.DatabaseWrapper.display_name
attribute with the name of the database that your backend works with. Django
may use it in various messages, such as in system checks.SchemaEditor._alter_column_type_sql() is now
model rather than table.SchemaEditor._create_index_name() is now
table_name rather than model.FOR UPDATE OF support, set
DatabaseFeatures.has_select_for_update_of = True. If the database
requires that the arguments to OF be columns rather than tables, set
DatabaseFeatures.select_for_update_of_column = True.Window
expressions, set DatabaseFeatures.supports_over_clause to True. You
may need to customize the DatabaseOperations.window_start_rows_start_end()
and/or window_start_range_start_end() methods.DatabaseOperations.cast_char_field_without_max_length attribute with the
database data type that will be used in the
Cast function for a CharField if the
max_length argument isn’t provided.DatabaseCreation._clone_test_db() and
get_test_db_clone_settings() is now suffix rather
than number (in case you want to rename the signatures in your backend
for consistency). django.test also now passes those values as strings
rather than as integers.DatabaseIntrospection.get_sequences() method based on the stub in
BaseDatabaseIntrospection.The end of upstream support for Oracle 11.2 is Dec. 2020. Django 1.11 will be supported until April 2020 which almost reaches this date. Django 2.0 officially supports Oracle 12.1+.
MySQL’s default isolation level, repeatable read, may cause data loss in
typical Django usage. To prevent that and for consistency with other databases,
the default isolation level is now read committed. You can use the
DATABASES setting to use a different isolation level, if needed.
AbstractUser.last_name max_length increased to 150¶A migration for django.contrib.auth.models.User.last_name is included.
If you have a custom user model inheriting from AbstractUser, you’ll need
to generate and apply a database migration for your user model.
If you want to preserve the 30 character limit for last names, use a custom form:
from django.contrib.auth.forms import UserChangeForm
class MyUserChangeForm(UserChangeForm):
last_name = forms.CharField(max_length=30, required=False)
If you wish to keep this restriction in the admin when editing users, set
UserAdmin.form to use this form:
from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.models import User
class MyUserAdmin(UserAdmin):
form = MyUserChangeForm
admin.site.unregister(User)
admin.site.register(User, MyUserAdmin)
QuerySet.reverse() and last() are prohibited after slicing¶Calling QuerySet.reverse() or last() on a sliced queryset leads to
unexpected results due to the slice being applied after reordering. This is
now prohibited, e.g.:
>>> Model.objects.all()[:2].reverse()
Traceback (most recent call last):
...
TypeError: Cannot reverse a query once a slice has been taken.
To help prevent runtime errors due to incorrect ordering of form field arguments, optional arguments of built-in form fields are no longer accepted as positional arguments. For example:
forms.IntegerField(25, 10)
raises an exception and should be replaced with:
forms.IntegerField(max_value=25, min_value=10)
call_command() validates the options it receives¶call_command() now validates that the argument parser of the command being
called defines all of the options passed to call_command().
For custom management commands that use options not created using
parser.add_argument(), add a stealth_options attribute on the command:
class MyCommand(BaseCommand):
stealth_options = ('option_name', ...)
For example:
models.Index(['headline', '-pub_date'], 'index_name')
raises an exception and should be replaced with:
models.Index(fields=['headline', '-pub_date'], name='index_name')
This will appear as a backwards-incompatible change (IntegrityError:
FOREIGN KEY constraint failed) if attempting to save an existing model
instance that’s violating a foreign key constraint.
Foreign keys are now created with DEFERRABLE INITIALLY DEFERRED instead of
DEFERRABLE IMMEDIATE. Thus, tables may need to be rebuilt to recreate
foreign keys with the new definition, particularly if you’re using a pattern
like this:
from django.db import transaction
with transaction.atomic():
Book.objects.create(author_id=1)
Author.objects.create(id=1)
If you don’t recreate the foreign key as DEFERRED, the first create()
would fail now that foreign key constraints are enforced.
Backup your database first! After upgrading to Django 2.0, you can then rebuild tables using a script similar to this:
from django.apps import apps
from django.db import connection
for app in apps.get_app_configs():
for model in app.get_models(include_auto_created=True):
if model._meta.managed and not (model._meta.proxy or model._meta.swapped):
for base in model.__bases__:
if hasattr(base, '_meta'):
base._meta.local_many_to_many = []
model._meta.local_many_to_many = []
with connection.schema_editor() as editor:
editor._remake_table(model)
This script hasn’t received extensive testing and needs adaption for various cases such as multiple databases. Feel free to contribute improvements.
In addition, because of a table alteration limitation of SQLite, it’s prohibited
to perform RenameModel and
RenameField operations on models or
fields referenced by other models in a transaction. In order to allow migrations
containing these operations to be applied, you must set the
Migration.atomic attribute to False.
The SessionAuthenticationMiddleware class is removed. It provided no
functionality since session authentication is unconditionally enabled in
Django 1.10.
The default HTTP error handlers (handler404, etc.) are now callables
instead of dotted Python path strings. Django favors callable references
since they provide better performance and debugging experience.
RedirectView no longer silences
NoReverseMatch if the pattern_name doesn’t exist.
When USE_L10N is off, FloatField and
DecimalField now respect DECIMAL_SEPARATOR
and THOUSAND_SEPARATOR during validation. For example, with the
settings:
USE_L10N = False
USE_THOUSAND_SEPARATOR = True
DECIMAL_SEPARATOR = ','
THOUSAND_SEPARATOR = '.'
an input of "1.345" is now converted to 1345 instead of 1.345.
Subclasses of AbstractBaseUser are no
longer required to implement get_short_name() and get_full_name().
(The base implementations that raise NotImplementedError are removed.)
django.contrib.admin uses these methods if implemented but doesn’t
require them. Third-party apps that use these methods may want to adopt a
similar approach.
The FIRST_DAY_OF_WEEK and NUMBER_GROUPING format settings are now
kept as integers in JavaScript and JSON i18n view outputs.
assertNumQueries() now ignores
connection configuration queries. Previously, if a test opened a new database
connection, those queries could be included as part of the
assertNumQueries() count.
The default size of the Oracle test tablespace is increased from 20M to 50M and the default autoextend size is increased from 10M to 25M.
To improve performance when streaming large result sets from the database,
QuerySet.iterator() now fetches 2000 rows at a time instead of 100.
The old behavior can be restored using the chunk_size parameter. For
example:
Book.objects.iterator(chunk_size=100)
Providing unknown package names in the packages argument of the
JavaScriptCatalog view now raises ValueError
instead of passing silently.
A model instance’s primary key now appears in the default Model.__str__()
method, e.g. Question object (1).
makemigrations now detects changes to the model field limit_choices_to
option. Add this to your existing migrations or accept an auto-generated
migration for fields that use it.
Performing queries that require automatic spatial transformations now raises NotImplementedError
on MySQL instead of silently using non-transformed geometries.
django.core.exceptions.DjangoRuntimeWarning is removed. It was only used
in the cache backend as an intermediate class in CacheKeyWarning’s
inheritance of RuntimeWarning.
Renamed BaseExpression._output_field to output_field. You may need
to update custom expressions.
In older versions, forms and formsets combine their Media with widget
Media by concatenating the two. The combining now tries to preserve
the relative order of elements in each list.
MediaOrderConflictWarning is issued if the order can’t be preserved.
django.contrib.gis.gdal.OGRException is removed. It’s been an alias for
GDALException since Django 1.8.
Support for GEOS 3.3.x is dropped.
The way data is selected for GeometryField is changed to improve
performance, and in raw SQL queries, those fields must now be wrapped in
connection.ops.select. See the Raw queries note in
the GIS tutorial for an example.
context argument of Field.from_db_value() and Expression.convert_value()¶The context argument of Field.from_db_value() and
Expression.convert_value() is unused as it’s always an empty dictionary.
The signature of both methods is now:
(self, value, expression, connection)
instead of:
(self, value, expression, connection, context)
Support for the old signature in custom fields and expressions remains until Django 3.0.
django.db.backends.postgresql_psycopg2 module is deprecated in favor
of django.db.backends.postgresql. It’s been an alias since Django 1.9.
This only affects code that imports from the module directly. The
DATABASES setting can still use
'django.db.backends.postgresql_psycopg2', though you can simplify that by
using the 'django.db.backends.postgresql' name added in Django 1.9.django.shortcuts.render_to_response() is deprecated in favor of
django.shortcuts.render(). render() takes the same arguments
except that it also requires a request.DEFAULT_CONTENT_TYPE setting is deprecated. It doesn’t interact well
with third-party apps and is obsolete since HTML5 has mostly superseded
XHTML.HttpRequest.xreadlines() is deprecated in favor of iterating over the
request.field_name keyword argument to QuerySet.earliest() and
QuerySet.latest() is deprecated in favor of passing the field
names as arguments. Write .earliest('pub_date') instead of
.earliest(field_name='pub_date').These features have reached the end of their deprecation cycle and are removed in Django 2.0.
See Features deprecated in 1.9 for details on these changes, including how to remove usage of these features.
weak argument to django.dispatch.signals.Signal.disconnect() is
removed.django.db.backends.base.BaseDatabaseOperations.check_aggregate_support()
is removed.django.forms.extras package is removed.assignment_tag helper is removed.host argument to SimpleTestCase.assertsRedirects() is removed.
The compatibility layer which allows absolute URLs to be considered equal to
relative ones when the path is identical is also removed.Field.rel and Field.remote_field.to are removed.on_delete argument for ForeignKey and OneToOneField is now
required in models and migrations. Consider squashing migrations so that you
have fewer of them to update.django.db.models.fields.add_lazy_relation() is removed.cursor.execute().django.contrib.auth.tests.utils.skipIfCustomUser() is removed.GeoManager and GeoQuerySet classes are removed.django.contrib.gis.geoip module is removed.supports_recursion check for template loaders is removed from:django.template.engine.Engine.find_template()django.template.loader_tags.ExtendsNode.find_template()django.template.loaders.base.Loader.supports_recursion()django.template.loaders.cached.Loader.supports_recursion()load_template and load_template_sources template loader methods
are removed.template_dirs argument for template loaders is removed:django.template.loaders.base.Loader.get_template()django.template.loaders.cached.Loader.cache_key()django.template.loaders.cached.Loader.get_template()django.template.loaders.cached.Loader.get_template_sources()django.template.loaders.filesystem.Loader.get_template_sources()django.template.loaders.base.Loader.__call__() is removed.exception parameter
is removed.mime_type attribute of django.utils.feedgenerator.Atom1Feed and
django.utils.feedgenerator.RssFeed is removed.app_name argument to include() is removed.admin.site.urls) as the first
argument to include() is removed.Field._get_val_from_obj() is removed.django.template.loaders.eggs.Loader is removed.current_app parameter to the contrib.auth function-based views is
removed.callable_obj keyword argument to
SimpleTestCase.assertRaisesMessage() is removed.allow_tags attribute on ModelAdmin methods is
removed.enclosure keyword argument to SyndicationFeed.add_item() is
removed.django.template.loader.LoaderOrigin and
django.template.base.StringOrigin aliases for
django.template.base.Origin are removed.See Features deprecated in 1.10 for details on these changes.
makemigrations --exit option is removed.get_srid() and set_srid() methods of
django.contrib.gis.geos.GEOSGeometry are removed.get_x(), set_x(), get_y(), set_y(), get_z(), and
set_z() methods of django.contrib.gis.geos.Point are removed.get_coords() and set_coords() methods of
django.contrib.gis.geos.Point are removed.cascaded_union property of django.contrib.gis.geos.MultiPolygon
is removed.django.utils.functional.allow_lazy() is removed.shell --plain option is removed.django.core.urlresolvers module is removed in favor of its new
location, django.urls.CommaSeparatedIntegerField is removed, except for support in historical
migrations.Context.has_key() method is removed.django.core.files.storage.Storage.accessed_time(),
created_time(), and modified_time() methods is removed.Meta.default_related_name is set is removed.__search lookup is removed._apply_rel_filters() method is removed.User.is_authenticated() and User.is_anonymous() as methods
rather than properties is no longer supported.Model._meta.virtual_fields attribute is removed.virtual_only in Field.contribute_to_class() and
virtual in Model._meta.add_field() are removed.javascript_catalog() and json_catalog() views are removed.django.contrib.gis.utils.precision_wkt() is removed.OneToOneField to a
parent_link is removed.Widget._format_value() is removed.FileField methods get_directory_name() and get_filename() are
removed.mark_for_escaping() function and the classes it uses: EscapeData,
EscapeBytes, EscapeText, EscapeString, and EscapeUnicode are
removed.escape filter now uses django.utils.html.conditional_escape().Manager.use_for_related_fields is removed.Manager inheritance follows MRO inheritance rules. The requirement
to use Meta.manager_inheritance_from_future to opt-in to the behavior is
removed.settings.MIDDLEWARE_CLASSES is
removed.Nov 02, 2020